Total River Length Research Articles

New approach for evaluating habitat stability using scarce records for both historical and contemporary specimens: a case study using Carabidae specimen records

AbstractNatural history collections, such as specimen records, are crucial resources for conservation and habitat management. However, these data are usually scarce compared to physical environmental data (e.g., digital terrain maps) that we often have little species data and a lot of physical environmental data with which to evaluate habitats. In this paper, we propose a method for evaluating habitat stability using scarce natural history records and abundant physical environmental data. We used both historical and contemporary specimen records of carabid beetles (areas in which records of the same species were recorded during both periods) and evaluated the attributes of these areas using terrain characteristics. We found two common terrain characteristics among the occupied areas: large total river length and low variation in elevation. These terrain characteristics suggest that habitats of carabid species have been conserved in disturbed and wet environments for a long time. These results are consistent with the ecological characteristics of carabid beetles. Our study shows that scarce natural history collections, combined with ingenuity, can be useful for evaluating habitats.

Using volunteered geographical information to map the November 2012 floods in Slovenia

Abstract. Volunteered geographical information represents a promising field in the monitoring and mapping of natural disasters. The contributors of volunteered geographical information have the advantage that they are at the location of the natural disaster at exactly the time when the disaster happened. Therefore, they can provide the most complete account of the extent of the damage. This is not always possible when applying photogrammetric or remote-sensing methods, as prior to the data acquisition an order to carry out the measurements has to be made. On 5 and 6 November 2012 almost half of Slovenia was badly affected by floods. The gathering of volunteered geographical information in the form of images and videos of these floods is presented. Two strategies were used: (1) a public call for volunteered contributions and (2) a web search for useful images and their authors. The authorship of these images was verified with every contributor. In total, 15 contributors provided 102 terrestrial and aerial images and one aerial video, with 45% classified as potentially useful. For actual flood mapping 22 images and 12 sequences from video were used. With the help of the volunteered images 12% of the most severely affected river sections were mapped. Altogether, 1195.3 ha of flooded areas outside of the usual river beds along a total river length of 48 km were mapped. The results are compared with those from satellite mapping of the same floods, which successfully covered 18% of the most affected river sections.

Do Concentrations of Ethinylestradiol, Estradiol, and Diclofenac in European Rivers Exceed Proposed EU Environmental Quality Standards?

This study used a geographic based water model to predict the environmental concentrations of three pharmaceuticals, 17α-ethinylestradiol (EE2), 17β-estradiol (E2), and diclofenac throughout European rivers. The work was prompted by the proposal of the European Community (COM(2011)876) to consider these chemicals as candidates for future control via environmental quality standards (EQS). National drug consumption information, excretion, national water use, and sewage removal rates, were used to derive per capita sewage effluent values for the European countries . For E2, excretion rates of the natural hormone and national demographics were also included. Incorporating this information into the GWAVA model allowed water concentrations throughout Europe's rivers to be predicted. The mean concentration from the expected sewage discharge scenario indicated that 12% by length of Europe's rivers would reach concentrations greater than the proposed 0.035 ng/L EQS for EE2. For several countries, between a quarter and a third of their total river length would fail such an EE2 EQS. For E2, just over 1% by length of rivers would reach concentrations greater than the 0.4 ng/L proposed EQS, while just over 2% by length of rivers would reach concentrations greater than the proposed EQS of 100 ng/L for diclofenac.

Mechanisms of carbon storage in mountainous headwater rivers

Published research emphasizes rapid downstream export of terrestrial carbon from mountainous headwater rivers, but little work focuses on mechanisms that create carbon storage along these rivers, or on the volume of carbon storage. Here we estimate organic carbon stored in diverse valley types of headwater rivers in Rocky Mountain National Park, CO, USA. We show that low-gradient, broad valley bottoms with old-growth forest or active beaver colonies store the great majority of above- and below-ground carbon. These laterally unconfined valley segments constitute <25% of total river length, but store ∼75% of the carbon. Floodplain sediment and coarse wood dominate carbon storage. Our estimates of riverine carbon storage represent a previously undocumented but important carbon sink. Our results indicate that: not all mountainous rivers rapidly export carbon; not all valley segments are equally important in carbon storage; and historical changes in riverine complexity have likely reduced carbon storage.

Benthic and hyporheic invertebrate assemblages along a flow intermittence gradient: effects of duration of dry events

1. A large proportion of the total river length on Earth comprises rivers that are temporary in nature. However, the effects of periodical dry events have received far less attention from ecologists than those of floods and low flows. 2. This study concomitantly examined the effects of flow intermittence on invertebrates from the streambed surface and from a depth of 30 cm in the hyporheic zone. Invertebrates were collected during 3 years in the Albarine River, France, before and after summer dry events from 18 sites (seven were perennial) distributed along a longitudinal flow intermittence gradient. 3. I predicted benthic and hyporheic density and taxonomic richness to decrease, and assemblage composition to shift from desiccation-sensitive to desiccation-resistant taxa with increased dry event duration. Second, I predicted benthic and hyporheic assemblages from sites that dried for longer periods to be nested subsets of assemblages from sites that dried for shorter periods. Last, I predicted a convergence in benthic and hyporheic assemblage composition with increasing duration of dry events, resulting from increased vertical migration of benthic taxa into the hyporheic sediments to cope with dry events. 4. Increased dry event duration in the Albarine River led to a decrease in both benthic and hyporheic density and taxonomic richness. Invertebrate assemblage composition shifted along the gradient of increasing flow intermittence, but broad taxonomic overlap between perennial and temporary reaches and nestedness patterns indicated that these shifts were because of the loss of taxa susceptible to drying rather than selection for desiccation-resistant specialists. 5. Assemblage composition between benthic and hyporheic invertebrates diverged with increasing dry event duration, suggesting that the hyporheic zone did not act as a refuge during dry events in this river. 6. Quantitative studies on the relationships between ecology and intermittence are still rare but are needed to predict the consequences of future changes in flow intermittence. The relationships found in this study should be tested across a wide range of temporary rivers to better evaluate the generality of these findings.

Influence of data sources and processing methods on theoretical river network quality

Influence of data sources and processing methods on theoretical river network quality Stream ecosystem research and water resource management need to be considered over broad spatial scales. Moreover, the investigation of the spatial configuration and habitat characteristics of streams requires an accurate and precise spatial framework to reflect a catchment's physical reality that can successfully explain observed patterns at smaller scales. In this sense, geographic information systems represent an essential tool to satisfy the needs of researchers and managers. Specifically, theoretical river networks (TRNs) extracted from digital elevation models (DEMs) have become much more common in recent years, as they can provide a suitable spatial network and hierarchical organisation to sort out river ecosystem information from reach to catchment levels. Nevertheless the quality of the extracted TRN depends greatly on the spatial resolution of the DEM and the methodology used in the network extraction processes. In this study, we compare the quality of 9 TRNs extracted from DEMs with different spatial resolutions ranging from regional (5 m) to national (25 m) and global scales (90 m) using the ArcHydro, Hec-GeoHMS and Netstream software packages. To achieve our goal, we compared (i) the DEM-derived slope; (ii) the spatial accuracy of the TRNs in relation to a control river network; (iii) the structure of the TRNs through analysis of the number of river segments, average river segment length and total river length by stream order, drainage density and the mean upstream slope throughout the TRN; and (iv) the ability of variables derived from TRNs to discriminate among stream types classified according to flow type and substrate composition. We demonstrated that not only DEM spatial resolution but also the DEM data source and raster creation process exert an important influence on terrain characteristics derived from DEMs and TRN properties. Moreover, TRNs extracted with NetStream generally showed better performance than those extracted with ArchHydro and HecGeoHMS. Nevertheless, river network extraction quality, DEM spatial resolution and extraction algorithms exhibit complex relationships due to the large number of interacting factors.

A simple management tool for planning the restoration of river longitudinal connectivity at watershed level: priority indices for fish passes

Summary The present study aimed at defining and testing a simple and widely applicable management tool, based on already available or easily collectable data, which could allow Watershed Authorities to prioritize the interventions for river longitudinal connectivity restoration, reopening fish migration routes. The proposed priority indices for fish passes are based on obstacle characteristics, length of the potential reopened reach and fish species distribution and migratory behaviour. The indices were applied to two Italian watersheds (Arno and Magra Rivers) covering a total river length of more than 400 km. The priority lists produced by the application can function as a first step in defining a watershed restoration plan and could help the Watershed Authorities to address the available resources towards more detailed studies to be carried out at sites classified with the higher priority levels. This is the case of the Regional Natural Park Monte Marcello-Magra, where, within a recently funded LIFE+ project (P.A.R.C. –‘Petromyzon And River Continuity’), the first results of the priority indices application will be analyzed in greater detail and will consequently lead to the design and construction of fish passes to restore fish migration routes with a particular focus on sea lamprey (Petromyzon marinus).

A national risk assessment for intersex in fish arising from steroid estrogens

The occurrence of intersex fish is widespread in the rivers of England and Wales. The extent of intersex in fish populations is believed to be strongly linked to their exposure to steroid estrogens. The present study presents, to our knowledge, the first national, catchment-based risk assessment for steroid estrogens in the world. A graphical information system-based model predicted the concentrations of estradiol (E2), estrone, and ethinylestradiol, which were combined and compared with known biological effect levels to predict the risk of endocrine disruption for 10,313 individual river reaches (21,452 km) receiving effluent from more than 2000 sewage treatment plants serving more than 29 million people. The large scale of this assessment underlines the usefulness of computer-based risk assessment methods. Overall, 61% [corrected] of the modeled reaches (all percentages are in terms of the total river length modeled) in England and Wales were predicted to be not at risk from endocrine disruption (mean concentrations, <1 ng/L E2 equivalents). A large range existed in the percentage of river reaches at risk in the various regions, from 5% in Wales to 67% in the Thames catchment. Important factors influencing this proportion are the population density, particularly their location, and the available dilution. A very small proportion of reaches (approximately 1-3%) were predicted to be at high risk (>10 ng/L E2 equivalents). Many of these high-risk reaches, however, were ditches, which were composed almost entirely of sewage effluent. The model could be applied equally well to any other chemical of concern emanating from the human population that would be impractical to assess by measurement.

Chemical weathering of carbonates and silicates in the Han River basin, South Korea

A detailed investigation of the fluvial geochemistry of the Han River system allows to estimate the rates of chemical weathering and the consumption of CO 2. The Han River drains approximately 26,000 km 2 and is the largest river system in South Korea in terms of both water discharge and total river length. It consists of two major tributaries: the North Han River (NHR) and the South Han River (SHR). Distinct differences in basin lithology (silicate vs. carbonate) between the NHR and SHR provide a good natural laboratory in which to examine weathering processes and the influence of basin geology on water quality. The concentrations of major elements and the Sr isotopic compositions were obtained from 58 samples collected in both summer and winter along the Han River system in both 2000 and 2006. The concentrations of dissolved loads differed considerably between the NHR and SHR; compared with the SHR, the NHR had much lower total dissolved solids (TDS), Sr, and major ion concentrations but a higher Si concentration and 87Sr/ 86Sr ratio. A forward model showed that the dissolved loads in the NHR came primarily from silicate weathering (55 ± 11%), with a relatively small portion from carbonates (30 ± 14%), whereas the main contribution to the dissolved loads in the SHR was carbonate weathering (82 ± 3%), with only 11 ± 4% from silicates. These results are consistent with the different lithologies of the two drainage basins: silicate rocks in the NHR versus carbonate rocks in the SHR. Sulfuric acid derived from sulfide dissolution in coal-containing sedimentary strata has played an important role in carbonate weathering in the SHR basin, unlike in the NHR basin. The silicate weathering rate (SWR) was similar between the NHR and SHR basins, but the rate of CO 2 consumption in the SHR basin was lower than in the NHR basin due to an important role of sulfuric acid derived from pyrite oxidation.

Sugar Cane Industry as a Source of Water Pollution – Case Study on the Situation in Ipojuca River, Pernambuco, Brazil

The Ipojuca river, a river in Northeast Brazil extending from west to east, is situated in the semiarid interior and rainy coastal zone of Pernambuco state. The river basin covers an area of 3,514 km2, with a total river length of 215 km. The water flow regime is characterized by the annual change from dry to rainy season as well as periodically occurring dry cycles. Mean flow rates vary between 2 and 35 m3 s−1. The dominant impacts on water quality of the river are domestic sewage input in the upper catchment and sugar cane cultivation and processing in the lower catchment. Long-term monitoring data used to demonstrate the impact of sewage discharge on the river’s self-purification capacity indicated a severe change to the worse in the lower course. One reason is the use of stillage (wastewater from cane processing) for fertilization and irrigation (fertigation). Pathways of contamination have been identified by evaluating cultivation and processing techniques of a bio-alcohol factory with annexed sugar cane cultivation. The river’s main ecological problems are water heating, acidification, increased turbidity, oxygen imbalance, and increased coliform bacteria levels. Precipitation-related wash-off and wash-out causes significant contamination within one to two days after rainfall. The increase in coliform bacteria is a consequence of secondary contamination. To determine the impact of the sugar cane industry on the river, the Brazilian bio-alcohol program must be subject to a critical evaluation. Environmentally friendly sugar cane cultivation methods need to be developed, and sugar cane factories must use waste-reducing technologies and water cycling processes in order to protect the region’s water resources.

Integrated Evaluation of Water Quality and Quantity of the Yellow River

This study presents an integrated water quantity and quality management method for the entire Yellow River system where the eco-environment has been deteriorating and water quantity is very scarce. The supply and demand of water resources has been investigated. The integration of the concepts of water resources functional capacity and water resources functional deficit have been put forward, and their characteristics have been analyzed. The results, based on 1997 to 1999 data, indicate that approximately 39 percent of the total river length was of excellent to good quality, 26 percent was moderate, and 35 percent was poor to very poor. The total natural runoffs of the river were 31.8, 43.9, and 43.4 billion m3, and about 94, 65, and 71 percent of them were withdrawn for agricultural, industrial, and domestic uses in 1997, 1998, and 1999, respectively. The total water resources availabilities were 21.1, 28.8, and 29.2 billion m3 occupying about 66, 66, and 67 percent of the total runoffs in 1997, 1998, and 1999, respectively. From 1997 to 1999, the river could provide only 53 percent (on average) of the total water resources demand for the uses and discharge to the Bohai Sea; about 57 percent of the water deficiency resulted from pollution and 43 percent from quantity deficit. For the main pollution parameter (COD Mn ), the averages of water resources functional capacity and deficit were 29,571.54 and 199.70 kg, respectively; for NH 4-N, the averages of water resources functional capacity and deficit were 3774.26 and 113.08 kg, respectively. These demonstrated that the influence of NH 4-N on water resources availability was more than that of COD Mn and that the functional capacity was much higher than functional deficit, suggesting that the actual water quality was mostly better than the required one for water supply functions.

Use of remote sensing and geographical information systems to identify environmental features that influence the distribution of paramphistomosis in sheep from the southern Italian Apennines

A geographic information system (GIS) was constructed using remote sensing (RS) and landscape feature data together with Calicophoron daubneyi positive survey records from 197 georeferenced ovine farms with animals pasturing in a 3971 km 2 area of the southern Italian Apennines. The objective was to study the spatial distribution of this rumen fluke, identify environmental features that influence its distribution, and develop a preliminary risk assessment model. The GIS for the study area was constructed utilizing the following environmental variables: normalized difference vegetation index (NDVI), land cover, elevation, slope, aspect, and total length of rivers. These variables were then calculated for “buffer zones” consisting of the areas included in a circle of 3 km diameter centered on 197 farms. The environmental data obtained from GIS and RS and from data taken by the veterinarians on the field (stocking rate and presence of streams, springs and brooks on pasture) were analyzed by univariate (Spearman and ANOVA) and multivariate (discriminant) statistical analyses using the farm coprological status (positive/negative) as the dependent variable. Sheep on 32 of the 197 (16.2%) farms, were positive for C. daubneyi, with an average intensity of 52 epg. A multivariate stepwise discriminant analysis model was developed that included moors and heathland, sclerophyllous and coniferous forest vegetation, autumn–winter NDVI and presence of streams, springs and brooks on pasture. The variables entered in the model were also correlated with C. daubneyi positive farms in the univariate tests and are consistent with the environmental requirements of C. daubneyi and its snail intermediate host.

The impact of Phytophthora disease on riparian populations of common alder (Alnus glutinosa) in southern Britain

SummaryIn 1994 a survey was established to obtain information on Phytophthora disease of common alder (Alnus glutinosa) on the riverbanks of southern England and east Wales. Within an area of 70 000 km2 63 observation plots were set up on stretches of river over 8 m wide. Average alder densities varied widely in different parts of the survey area; from 0.7 to 22.2 trees per 100 m of river. From the density figures and data on the total length of rivers over 8 m wide within the survey area, it was estimated that there were approximately 585 000 alder trees growing on the banks of such rivers.In 1994 3.9% of the trees showed crown symptoms of Phytophthora disease, and an additional 1.2% of trees were dead, although not all of these had been killed by Phytophthora. The disease occurred widely through the survey area with an indication that the highest percentage of affected trees was to be found in the south‐east of England. Subsequent surveys showed that the combined percentage of symptomatic and dead trees rose to 6.0% in 1995 and to 7.9% in 1996. In the latter year, for an alder population of 585 000 trees, this would correspond to 32 800 symptomatic and 13 500 dead trees.The percentage of trees showing symptoms was seven times as high in trees growing within 1 m of the riverbank as in trees growing between 1 and 10 m of the bank. An examination of the relationships between disease incidence and various indices of water pollution revealed a positive association with total oxidized nitrogen. These results are discussed in relation to the biology and possible origin of the disease.

Predictive models for lesser kestrel Falco naumanni distribution, abundance and extinction in southern Spain

Environmental variables measured on 1:10,000 to 1:3,000,000-scale maps of southern Spain were used to build generalized linear models for presence/absence of lesser kestrel Falco naumanni colonies, extinction of colonies, and number of breeding pairs, in 6 × 6 km squares. Presence of breeding colonies in a square was positively associated with presence of urban areas, extent of non-irrigated cereal and sunflower crops, and mean annual rainfall, and negatively associated with extent of scrubland and forests. The model was statistically robust and had good predictive ability, correctly classifying 84% of the squares. Two alternative models were obtained for extinction of lesser kestrel colonies in a square. The first indicated extinctions where there were large areas of scrubland and low annual rainfall, and the second where there were very large or very small areas of non-irrigated cereal and sunflower crops. Although both were statistically significant, neither was very robust or had a good predictive ability. The number of lesser kestrel pairs breeding in a square showed a negative relationship with altitude, area of forest, and irrigated cultures, and a positive association with total length of rivers and streams. This model was not very robust and explained only 30·3% of the variance in kestrel numbers. The models indicate that some climatic and land-use variables, as measured on the available maps, are good predictors of the presence of lesser kestrel colonies in southern Spain, but less good at predicting the probability of extinction of colonies or the number of breeding pairs.

FLOWING WATER RESOURCES1

ABSTRACTUsing data related to stream order and the morphological characteristics associated with streams of different discharge rates, an estimate of the river resources of the United States is made. The national totals are: 3,200,000 miles total length of rivers; 15,000 square miles of river surface; and 29 cubic miles of water stored in river channels. Using the same techniques, more exact estimates may be made for individual river basins. Suggestions are given for application of the techniques and river data in the management of water resources.